If $8a + 3b + 8c = 9$ and $4x + 7y + 2z = -1$, what is $-64c - 64a - 24b - 8z - 16x - 28y$ ?
Answer: $= -64a - 24b - 64c - 16x - 28y - 8z$ $= (-8) \cdot (8a + 3b + 8c) + (-4) \cdot (4x + 7y + 2z)$ $= (-8) \cdot (9) + (-4) \cdot (-1)$ $= -72 + 4$ $= -68$